D. What is solar access?

Solar access can be described as allowing the sun to penetrate a building or be utilized by a solar collector on the surface of that building between 9 a.m. and 3 p.m. in midwinter. There are varying degrees of solar access. There is whole-site access where the area of yard to the north of the building, as well as the north wall and rooftop are protected from shading by other buildings and vegetation in midwinter. North-wall access refers to the protection from shadows in midwinter of only the north facade, which includes the north roof and north wall.

Although whole-site access is desirable for outdoor garden use, it can be very costly in terms of the use of land and may not affect household energy use. Energy-efficiency encompasses more than Just energy savings in houses and so the decreased density that results from whole-site access cannot be justified.

There is a third level of solar access, rooftop access, which aims to protect rooftop solar collector systems from shading at certain times. Although this level of solar access allows maximum density to be achieved, it forecloses too many options for future development. The definition of solar access depends on the definition of the solar collector (whether passive or active).

Figure 25. Heat losses from different residential building types.

Figure 26. The effect of window orientation and winter heating load.

Figure 27. Solar access in Sydney.

North-wall access is the level of access designed for in this handbook.

The protection of solar access to dwellings is crucial to the performance of passive solar architecture. The period between 9 a. m. and 3 p.m. in mid-winter, as shown in figure 27, has been generally accepted as a measure of solar access.

For mid-winter in Sydney, the azimuth of the sun is approximately 45 degrees at 9 a.m. and at 3 p.m. At noon, the altitude of the sun is approximately 30 degrees. The protection of solar access is discussed in a later chapter under detailed design guidelines.